This laboratory aims to understand the molecular basis of protein folding. The elucidation of the basic principles underlying the secondary and tertiary structure of proteins may allow us to design novel structures with predetermined properties. Our strategy involves both the dissection of proteins into fragments that mimic elusive folding intermediates and the generation of mutant proteins that selectively modify certain steps of the folding pathway. Since little is known at present about the folding of (3-sheet proteins, we have developed at CCNY, entirely from scratch, a model system based on the non-covalent association of fragments, which illustrates the extension of (3-sheets at atomic detail in solution. In this study, we have combined H-exchange experiments with multidimensional nuclear magnetic resonance NMR spectroscopy We have also used other complementary tools, from biophysics, biochemistry, chemistry and molecular biology to study the recombination of these fragments. Synthetic variants of these fragments with single amino acid substitutions, that replace one of the fragments in the above described model system, will be used in the near future to establish the B-strand of the amino acid residues. Also, we are currently studying a folding intermediate of thioredoxin using a combination of manual hydrogen exchange pulse labeling experiments and 2D-NMR spectroscopy. For this study, we have overexpressed and purified protein in quantities sufficient for NMR studies. The results of this structural analysis will be correlated with the kinetic data on the refolding of thioredoxin using stopped flow far- and near- UV CD and fluorescence spectroscopy, acquired in collaboration with Dr. Alan Chaffofte at the Pasteur Institute in Dec 93-Jan 94. Besides the folding of a-sheet proteins, our lab is also interested in the folding of the super family of a helical growth factor from our immune system. This super family is typified by interleukin-2 (lL-2), a lectin-like protein with a 4-a-helical bundle. The study of the folding of IL-2 and its interaction with carbohydrate moieties at high structural resolution is being examined. The results of the latter studies will most likely be beneficial to biotechnology.;